I recently visited an affiliate while traveling and the instruction on bench pressing itself was excellent, but there was no mention of how or when to spot. Everyone in the class seemed to be doing something completely different. Some were a mile away from their partner having conversations with other gym-goers, some were hovering over their partners basically tea-bagging them, and one girl was "spotting" her partner by standing next to her. Yes, like next to her—on the wrong side of the bar.
Bench pressing is the barbell lift most of the general population has been exposed to—and more often than not, exposed to incorrectly. When spotting, it's important to teach your members how to do it correctly so that no one is put at undue risk. Partial reps and sloppy set-up positions aside, the worst habits you might see in any given gym are a spotter who either is too handsy—assisting the entire movement and thus invalidating the lift—or a spotter who isn’t engaged and would only have front-row tickets to an accident were one to occur.